Atomic Carbon in APM 08279+5255 atz= 3.91

Abstract

We present a detection of [C I] 3P1-3P0 emission in the lensed quasar APM 08279+5255 at z = 3.91 using the IRAM Plateau de Bure interferometer. The [C I] line velocity and width are similar to the values of previously detected high-J CO and HCN lines in this source, suggesting that the emission from all of these species arises from the same region. The apparent luminosity of the [C I] line is L = (3.1 ± 0.4) × 1010 K km s-1 pc2, which implies a neutral carbon mass M = (4.4 ± 0.6)m-1 × 107 M☉, where m is the lensing magnification factor. The [C I] line luminosity is consistent with the large molecular gas mass inferred from the nuclear CO line luminosity (~1011m-1 M☉). We also present an upper limit on the H2O 110-101 line luminosity in APM 08279+5255 of L < 1.8 × 1010 K km s-1 pc2 (3 σ).